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Nitroreductases and the Anaerobic Degradation of Nitro Organics in Soil

Rahi, Russel
The anaerobic degradation of 2,4-dinitrophenol and number of nitro organic compounds with soil microbial communities was investigated in two experiments. The goal of this study is to develop a method for the isolation for nitroreductase enzymes responsible for the anaerobic transformation of nitro organic compounds. The degradation of 2,4-dintrophenol was studied with the coamendment of 2-nitroethyl benzene under anaerobic conditions and the change in concentration was measured with GC-FID. This experiment revealed that the coamendment had no effects on the degradation. For the second experiment anaerobic microcosms were set up using anaerobic mineral media and soil collected from Ray Harrell regional park (Broken Arrow, OK). Nitro organic compounds were used in this study include, 2,4-dinitrophenol, 2-amino-4-dinitrophenol, 4-amino-2-dinitrophenol, nitrobenzene, 2,4,6-trinitrotoluene and 4-amino-2,6-dinitrotoluene. After 50 days only 2,4-dinitrophenol microcosm showed a decline in concentration but reduction to amino compounds was not confirmed. The isolated DNA from this microcosm along with sludge DNA from WWTP was used to test 8 different primers targeting nitroreductases designed from 98 unique amino acid sequences of nitroreductase enzymes. Primers were used with different concentrations of MgCl2 and a gradient of temperature from 42 �C to 56 �C. The clone library analysis on the PCR amplification products did not succeed in recovering nitroreductases in this study.